Surface-enhanced Raman spectroscopy using linearly arranged gold nanoparticles embedded in nanochannels

Abstract

A micro/nanofluidic device containing linearly arranged gold nanoparticles embedded in nanochannels was developed for highly sensitive and highly efficient surface-enhanced Raman spectroscopy (SERS). The Si nanochannel array was fabricated using a photolithography-based process. The nanochannel width was controlled from 100 to 400 nm. Synthesized particles of mean diameter 100 nm were arranged linearly in the nanochannels, using a nanotrench-guided self-assembly process. We developed a process for integrating linearly arranged nanoparticles and micro/nanofluidic components. The particle geometry provided significant Raman enhancement. Furthermore, efficient Raman analysis was possible by scanning a laser spot, because the particles were arranged in one direction. The fabricated structures were evaluated for SERS using 4,4'-bipyridine molecules at concentrations of 1 mM and 10 µM. The Raman peaks was obtained from a few hot spots. The Raman spectra showed that the molecule-specific Raman intensities were correlated with the number of hot spots in the nanochannel.